This invention relates to an improved cleaning brush for removing contaminates from a photoconductor film used in electrophotographic processes.
In the production of copies by electrophotographic processes a continuous loop of photoconductor film is commonly used. This photoconductor film is charged initially, thereafter passed through an imaging section, a developing section and an image transfer section where the image on the photoconductor film is transferred to a paper to produce a copy of the image on the paper. The paper is subsequently passed through a fuser section where a toner image on the paper is fixed to the paper by elevated temperature and pressure in the fuser section. The photoconductor film then passes through a neutralization section and thereafter past a brush cleaner which removes contaminates from the film prior to passing the photoconductor film back through the primary charging section. Typically contaminates removed from the photoconductor film by the cleaning brush are recovered from the brush by the use of a vacuum suction device. This device may comprise a wide mouth vacuum fixture which is in engagement with the brush or it may comprise a housing around the brush which is adapted to draw a gaseous flow through the housing.
In such processes the central 11 inch portion of the photoconductor film is the most commonly used area of the film. In other words most copies produced are 11 inches in length and this length, referred to herein as width, is positioned perpendicular to the length of the film and this portion of the film is repeatedly used to produce copies 11 inches in width. As a result this central section of the photoconductor film is exposed to paper and to toner and other materials which may come in contact with the photoconductor film during the copying process. The brush is used to clean such materials from the entire width of the photoconductor film prior to re-charging the film in the primary charging section. It has been observed that the photoconductor film in the areas outside the central section becomes worn more rapidly by the cleaning brush than does the more actively used central portion of the photoconductive film. Further it has been observed that contaminants (scum) tend to accumulate on the photoconductive film outside the central portion to a greater extent than in the central portion of the film. This accumulation can result in a defect referred to frequently as charger rust defect. In other words as the photoconductor film passes through the successive charging, discharging and other steps the accumulated contaminates on the portions of the photoconductor film outside the central portion of the film result in poor image quality.
Accordingly a continuing effort has been directed to methods for developing an improved cleaning brush to minimize the accelerated wear on the end portions of the photoconductor film, reduce the scum and the incidence of charger rust defect and extend the life of the photoconductor film.
According to the present invention it has been found that an improved result is achieved by the use of a rotary cleaning brush for removing contaminates from a photoconductor film used in an electrophotographic process. The brush comprises a brush surface comprising brush fibers around a brush core, the brush surface having brush surface ends, a central portion of the brush surface having outer ends and end portions of the brush surface positioned between the brush surface ends and the outer ends, the end portions of the brush surface having a lower coefficient of friction with the film than the central portion of the brush surface.
In a further embodiment, the brush comprises a brush surface comprising brush fibers around a brush core, the brush surface having brush surface ends, a central portion of the brush surface having outer ends and a central portion outer diameter; and, end portions of the brush surface positioned between the brush surface ends and the outer ends and having an end portion outer diameter less than the central portion outer diameter.
The invention further comprises a method for extending the life of a photoconductor film in an electrophotographic process wherein the film is cleaned by a rotary brush, the method comprising: cleaning a middle portion of the film by contact with the brush at a first coefficient of friction; and, cleaning end portions of the film by contact with the brush at a second coefficient of friction, the second coefficient of friction being less than the first coefficient of friction.
It has also been found that improved results are achieved by a method for removing contaminates from a photoconductor film in an electrophotographic process, the method comprising: forming a rotary cleaning brush to have a central portion and end portions with the central portion having an outer diameter from about 0.01 to about 0.05 inches greater than the outer diameter of the end portions; supporting the rotary cleaning brush to engage the photoconductor film in its central portion at an engagement of from about 0.02 to about 0.07 inches; and passing the photoconductor film past and in engagement with the rotary cleaning brush to remove contaminants from the photoconductor film.
It has also been discovered that an improvement is achieved in a method for removing contaminants from a photoconductor film used in an electrophotographic process by passing the photoconductor film past and in engagement with a rotary cleaning brush with contaminants being at least partially removed from the cleaning brush, the improvement comprising forming the rotary cleaning brush to have a central portion which engages a central portion of the photoconductor film and end portions which engage end portions of the photoconductor film with an outer diameter of the central portion of the cleaner brush being from about 0.01 to about 0.05 inches greater than an outer diameter of the end portions of the cleaning brush.
It has further been discovered that an improvement is achieved in a method for removing contaminants from a photoconductor film used in an electrophotographic process by passing the film past and in engagement with a rotary cleaning brush with contaminants being at least partially removed from the cleaning brush, the improvement comprising: forming the rotary cleaning brush to have a central portion which engages a central portion of the photoconductor film and end portions which engage end portions of the photoconductor film and reducing the coefficient of friction between the end portions of the film and the end portions of the brush.